LCD panel photolithography process and mask

ABSTRACT

Disclosed is an LCD panel photolithography process, employed in a lithography system for manufacturing a plurality of LCD panel, comprising steps of: performing photolithography to a glass substrate with a first mask, and the first mask comprises a plurality of sets of alignment marks corresponding to a plurality of following masks thereafter, and a plurality of sets of alignment marks corresponding to the plurality of following masks thereafter are formed on the glass substrate; and employing the plurality of sets of alignment marks on the glass substrate respectively, to perform alignment procedure and photolithography for the plurality of following masks with the plurality of sets of alignment marks on the glass substrate to form patterns; wherein corresponding to the same LCD panel area, the plurality of sets of alignment marks on the glass substrate have different position coordinates respectively.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of a U.S. patent application Ser. No. 13/216,729,filed on Aug. 24, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a photolithography process toa glass substrate and a mask thereof, and more particularly to an LCDpanel photolithography process and a mask thereof, to prevent the reworkand abandonment circumstances of the glass substrate cause of aligningthe alignment mark of the wrong mask in the alignment procedure of thelithography system. Accordingly, the manufacture yield rate of LCD panelcan be improved.

2. Description of Prior Art

Please refer to FIG. 1. When the LCD panel is manufactured, alithography system (such as the lithography system of Canon) is used. Anissue of a certain shift of the entire patterns occurs in some realmanufactures. After the investigation, the reason is that the alignmentmark of the wrong mask is aligned in the alignment procedure to resultin the abnormal pattern appears. With depth analysis and then the rootcause is found, the structure design of the alignment marks inevitablyresults in such exception. Hereafter, the basic principle of analignment system of Canon lithography system is introduced below:

Please refer to FIG. 2, which shows a structure diagram of an alignmentsystem. The light generated by the light source passes through the mainoptical system and reaches the mask and the glass substraterespectively. After reflection, the image of the alignment marks A, C onthe mask and the image of the alignment mark B on the glass substratepasses through the objective lens and the alignment scope. Then, theseimages are fetched by the CCD. Thereafter, the images of the alignmentmarks A, B, C are transmitted to the image processor and then shown onthe monitor. When the center of the alignment mark B coincides with thecenter of the alignment marks A, C, it means that the alignmentprocedure succeeds. If the center of the alignment mark B does notcoincide with the center of the alignment marks A, C, the load system ofthe glass substrate is actuated to move the glass substrate till thecenter of the alignment mark B coincides with the center of thealignment marks A, C. Then the alignment procedure before thephotolithography process is completed.

Please refer to FIG. 3 shows a diagram of an arrangement for thealignment marks of different masks according to prior art. In previousmasks, the arrangement of alignment marks is linear symmetric designed,even for the arrangement of alignment marks of different masks. Besides,the distances between the alignment marks of different masks are all thesame. As shown in the figure, there are alignment marks both at top andbottom of the LCD panels and D₂=D₃= . . . =D_(n) (The alphabet nrepresents the layer of mask). In figure, five masks are illustratedwith D₂=D₃=D₄=D₅, the design defect in previous masks is when one maskis employed for performing the alignment procedure, but the shapes ofthe alignment marks of different masks are all the same and thepositions are linear symmetric designed. Thereof, the lithography systemcannot judge which mask the alignment mark employed in the alignmentprocedure belongs to. Even the alignment mark of the wrong mask isemployed for alignment, the alignment procedure still can succeed andcomplete. Consequently, the circumstance that the wrong mask is alignedoccurs and results in the issue of the certain shift of the entirepatterns shown in FIG. 1. In the illustration of five masks withD₂=D₃=D₄=D₅, when the second mask is aligned, and the third mask, fourthmask and the fifth mask exist. When the second mask is being aligned,the lithography system misses the alignment mark of the second mask andaligns with the alignment mark of the third mask because the position ofthe glass substrate is shifted. Because no differences exist between thealignment mark of the second mask and the alignment mark of third mask,the lithography system of the user considers the alignment procedure iscompleted. Then, the photolithography process is performed andcompleted. The issue of the certain shift of the entire patterns shownin FIG. 1 occurs due to aligning with the wrong mask. Accordingly, ahuge number of the glass substrates have to rework or abandoned andleads to an enormous lost.

Consequently, there is a need to provide an LCD panel photolithographyprocess and a mask thereof.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide an LCD panelphotolithography process and a mask thereof to prevent the rework andabandonment circumstances of the glass substrate happened cause ofemploying the alignment mark of the wrong mask in the alignmentprocedure of the lithography system. Accordingly, the manufacture yieldrate of LCD panel can be improved.

For realizing the aforesaid objective, the present invention provides anLCD panel photolithography process and a mask thereof, employed in alithography system for manufacturing a plurality of LCD panel. The LCDpanel photolithography process of the present invention comprises stepsbelow: performing photolithography to a glass substrate formanufacturing the plurality of LCD panels with a first mask, and thefirst mask comprises a plurality of sets of alignment markscorresponding to a plurality of following masks thereafter, and aplurality of sets of alignment marks corresponding to the plurality offollowing masks thereafter are formed on the glass substrate; andemploying the plurality of sets of alignment marks on the glasssubstrate corresponding to the plurality of following masks thereafterrespectively, to perform alignment procedure and photolithography forthe plurality of following masks with the plurality of sets of alignmentmarks on the glass substrate according to a sequence of the plurality offollowing masks to form patterns; wherein corresponding to the same LCDpanel area, the plurality of sets of alignment marks on the glasssubstrate needed for the plurality of following masks have differentposition coordinates respectively.

In one embodiment of the LCD panel photolithography process according tothe present invention, after the step of performing photolithography tothe glass substrate with the first mask, the plurality of sets ofalignment marks formed on the glass substrate are at two sides of theplurality of LCD panel areas, and corresponding to the same LCD panelarea, each set of alignment marks comprises at least two alignment marksat the two sides, and the at least two alignment marks have differentopposite distances.

In one embodiment of the LCD panel photolithography process according tothe present invention, corresponding to the same LCD panel area, theopposite distances between the at least two alignment marks of the eachset of alignment marks are gradually increased or decreased in sequence.

In one embodiment of the LCD panel photolithography process according tothe present invention, corresponding to the same LCD panel area, theopposite distances between the at least two alignment marks of the eachset of alignment marks are gradually increased and then decreased insequence.

In one embodiment of the LCD panel photolithography process according tothe present invention, the plurality of sets of alignment marks formedon the glass substrate have respective x-coordinates and y-coordinatesrelative to an arbitrary side of the same LCD panel area.

For realizing the aforesaid objective, the present invention providesanother LCD panel photolithography process, employed in a lithographysystem for manufacturing a plurality of LCD panel to performphotolithography to a glass substrate for manufacturing the plurality ofLCD panels, comprising: performing photolithography to a glass substratewith a first mask, and the first mask has a plurality of sets ofalignment marks corresponding to a plurality of following masksthereafter, and a plurality of sets of alignment marks corresponding tothe plurality of following masks thereafter are formed on the glasssubstrate; and performing photolithography to the glass substrate with asecond mask, which is the last mask in the plurality of following masksthereafter, and the second mask comprises respective sets of alignmentmarks corresponding to respective following masks thereafter, andrespective sets of alignment marks corresponding to the respectivefollowing masks thereafter are formed on the glass substrate; whereinafter the photolithography of the first mask is performed, the pluralityof sets of alignment marks on the glass substrate needed for theplurality of following masks have different position coordinatesrespectively corresponding to the same LCD panel area; and after thephotolithography of the second mask is performed, the respective sets ofalignment marks on the glass substrate needed for the respectivefollowing masks also have different position coordinates respectivelycorresponding to the same LCD panel area.

In one embodiment of the LCD panel photolithography process according tothe present invention, after the step of performing photolithography tothe glass substrate with the first mask, the plurality of sets ofalignment marks formed on the glass substrate are at two sides of theplurality of LCD panel areas, and corresponding to the same LCD panelarea, each set of alignment marks comprises at least two alignment marksat the two sides, and the at least two alignment marks have differentopposite distances.

In one embodiment of the LCD panel photolithography process according tothe present invention, after the step of performing photolithography tothe glass substrate with the second mask, the respective sets ofalignment marks formed on the glass substrate are at two sides of theplurality of LCD panel areas, and corresponding to the same LCD panelarea, each set of alignment marks comprises at least two alignment marksat the two sides, and the two alignment marks have different oppositedistances.

For realizing the aforesaid objective, the present invention provides amask employed in an LCD panel photolithography process of a lithographysystem for manufacturing a plurality of LCD panel, for performingphotolithography to a glass substrate for manufacturing the plurality ofLCD panels. The mask of the present invention comprises: a plurality ofLCD panel areas, employed for forming patterns on the glass substrate;and a plurality of sets of alignment marks, employed for forming aplurality of sets of alignment marks corresponding to the plurality offollowing masks thereafter, and the plurality of sets of alignment marksfor the plurality of following masks have different position coordinateson the mask respectively.

In one embodiment of the mask according to the present invention, at twosides of the same LCD panel area, the respective sets of alignment markscorresponding to the respective masks comprises at least two alignmentmarks, and opposite distances between the at least two alignment marksof each set of alignment marks are gradually increased or decreased insequence.

According to the LCD panel photolithography process and the mask thereofof the present invention, the rework and abandonment circumstances ofthe glass substrate happened cause of employing the alignment mark ofthe wrong mask in the alignment procedure of the lithography system canbe prevented. Accordingly, the manufacture yield rate of LCD panel canbe improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of issue that a certain shift of the entirepatterns occurred in prior art.

FIG. 2 shows a structure diagram of an alignment system of thelithography system according to prior art.

FIG. 3 shows a diagram of an arrangement for the alignment marks ofdifferent masks according to prior art.

FIG. 4 shows a diagram of an arrangement for the alignment marks ofdifferent masks according to the present invention.

FIG. 5 shows a diagram of an arrangement of the alignment marks formedon a glass substrate with the alignment marks of different masksaccording to the present invention.

FIG. 6 shows a diagram of the alignment marks of different masksaccording to the present invention.

FIG. 7 shows a diagram of that the alignment procedure cannot completeif the alignment mark of the wrong mask is aligned in the alignmentsystem of the lithography system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For a better understanding the aforementioned content of the presentinvention, preferable embodiments are illustrated in conjunction withthe attached figures for further explanation:

Please refer to FIG. 4, FIG. 5 and FIG. 6. FIG. 4 shows a diagram of anarrangement for the alignment marks of different masks according to thepresent invention. FIG. 5 shows a diagram of an arrangement of thealignment marks formed on a glass substrate 20 with the alignment marksof different masks according to the present invention. FIG. 6 shows adiagram of the alignment marks of different masks according to thepresent invention.

One mask of the present invention shown in FIG. 4, FIG. 5 and FIG. 6 isemployed in a photolithography process of a lithography system shown inFIG. 2 for manufacturing a LCD panel. The mask of the present inventioncomprises a plurality of LCD panel areas 10-1 and a plurality of sets ofalignment marks. FIG. 4 shows merely one LCD panel area 10-1 for furtherexplaining the present invention in detail but FIG. 5 and FIG. 6 showsfour LCD panel areas 10-1 in practical. In this embodiment of thepresent invention, a manufacture process with five masks is illustratedbut more masks can be here according to the demands of the LCD panelmanufacture process. If processes with six masks or seven masks areneeded for manufacturing the LCD panel, a sixth set of alignment marksor a seventh set of alignment marks can be added further in the presentinvention. Shown in FIG. 4 is a first mask 10 of the present invention.The first mask 10 comprises a plurality of LCD panel areas 10-1. Theplurality of LCD panel areas 10-1 are employed for forming patterns onthe glass substrate 20. The first mask 10 comprises a second set ofalignment marks 12, a third set of alignment marks 14, a fourth set ofalignment marks 16 and a fifth set of alignment marks 18 correspondingto a second mask, a third mask, a fourth mask and a fifth mask,respectively. The second set of alignment marks 12, the third set ofalignment marks 14, the fourth set of alignment marks 16 and the fifthset of alignment marks 18 of the first mask 10 are arranged at top andbottom of the LCD panel area 10-1 oppositely and correspondingly. Inanother word, corresponding to the following masks, the first mask 10totally comprises three pairs, six alignment marks at the top and bottomrespectively but not limited thereto. Meanwhile, as aforementioned, thesixth set of alignment marks or the seventh set of alignment marks canbe further added in the present invention, if processes with six masksor seven masks are needed for manufacturing the LCD panel. At the topand bottom of the LCD panel, the sixth set of alignment marks or theseventh set of alignment marks can be added respectively. Accordingly,at the top of the bottom of each LCD panel 10-1 of the glass substrate20, five or six alignment marks can be formed. Each set of the alignmentmarks can be arranged at the top and bottom oppositely andcorrespondingly.

When the first mask 10 is employed in a photolithography processperformed to the glass substrate 20 of LCD panel, as shown in FIG. 5,the plurality of sets of alignment marks are formed on the glasssubstrate 20. The plurality of sets of alignment marks correspond to theplurality of following masks, i.e. the second set of alignment marks 22,the third set of alignment marks 24, the fourth set of alignment marks26 and the fifth set of alignment marks 28. Corresponding to the sameLCD panel area 10-1, such as the second set of alignment marks 22, thethird set of alignment marks 24, the fourth set of alignment marks 26and the fifth set of alignment marks 28 at the top of the LCD panel area10-1 on the first mask 10 have different position coordinatesrespectively, i.e. different x-coordinates and different y-coordinates.(Similarly, each set of the alignment marks at the bottom of the LCDpanel area 10-1 also have different x-coordinates and differenty-coordinates). In other words, relative to an arbitrary point on thefirst mask 10 or relative to an arbitrary side of the LCD panel area10-1, the respective x-coordinates and y-coordinates of the centers ofthe second set of alignment marks 12, the third set of alignment marks14, the fourth set of alignment marks 16 and the fifth set of alignmentmarks 18 are all different to one another. Namely, the second set ofalignment marks 12, the third set of alignment marks 14, the fourth setof alignment marks 16 and the fifth set of alignment marks 18 on thefirst mask 10 are not arranged with linear symmetric design, butarranged with offset design. For example, the opposite distances betweenthe second set of alignment marks 12, the third set of alignment marks14, the fourth set of alignment marks 16 and the fifth set of alignmentmarks 18 are gradually increased or decreased in sequence.Alternatively, the opposite distances between the second set ofalignment marks 12, the third set of alignment marks 14, the fourth setof alignment marks 16 and the fifth set of alignment marks 18 can begradually increased and then decreased in sequence.

Furthermore, in the embodiment of the present invention, the pluralityof sets of alignment marks is illustrated to be arranged at top andbottom of the LCD panel area 10-1 oppositely and correspondingly, butthe plurality of sets of alignment marks also can be arranged at theleft and right of the LCD panel area 10-1. Meanwhile, the arrangementwith offset design illustrated shown in FIG. 4 is a cascade rise or droparrangement but the present invention is not limited thereto. Thearrangement for the plurality of sets of alignment marks also can bealternate high-low design or waveform design, as long as the arrangementfor the plurality of sets of alignment marks is non-linear symmetricdesign and the serious problem of aligning the alignment mark of thewrong mask in prior art can be prevent.

Accordingly, as shown in FIG. 5, similarly, the second set of alignmentmarks 22, the third set of alignment marks 24, the fourth set ofalignment marks 26 and the fifth set of alignment marks 28 on the glasssubstrate 20 designed for corresponding to the second mask, the thirdmask, the fourth mask and the fifth mask have different positioncoordinates respectively i.e. different x-coordinates and differenty-coordinates. (Similarly, each set of the alignment marks at the bottomof the LCD panel area 10-1 also have different x-coordinates anddifferent y-coordinates). In other words, relative to an arbitrary pointon the glass substrate 20 or relative to an arbitrary side of the LCDpanel area 10-1, the respective x-coordinates and y-coordinates of thecenters of the second set of alignment marks 22, the third set ofalignment marks 24, the fourth set of alignment marks 26 and the fifthset of alignment marks 28 are all different to one another. Namely, thesecond set of alignment marks 22, the third set of alignment marks 24,the fourth set of alignment marks 26 and the fifth set of alignmentmarks 28 are not arranged with linear symmetric design, but arrangedwith offset design. For example, the opposite distances between thesecond set of alignment marks 12, the third set of alignment marks 14,the fourth set of alignment marks 16 and the fifth set of alignmentmarks 18 are gradually increased or decreased in sequence.Alternatively, the opposite distances between the second set ofalignment marks 22, the third set of alignment marks 24, the fourth setof alignment marks 26 and the fifth set of alignment marks 28 can begradually increased and then decreased in sequence. The following masks,such as the second mask, the third mask, the fourth mask and the fifthmask are employed to perform photolithography process to the glasssubstrate 20 to form patterns according to the sequence of aforesaidmasks. Therefore, when the third mask is employed for photolithographyprocess, wrong alignment with the alignment mark on the glass substrate20 for other masks, such as the second mask, the fourth mask or thefifth mask cannot happen. As shown in FIG. 7, if the alignment mark ofthe wrong mask is being aligned, the wrong alignment mark can be judgedaccording to the relative positions of the alignment marks A, C of thethird mask and the alignment mark B (24) on the glass substrate 20 shownon the monitor in the alignment system of the lithography system and thealignment procedure cannot complete.

Please further refer to FIG. 4, FIG. 5, FIG. 6 and FIG. 7. Asaforementioned on the first mask 10, the second set of alignment marks12, the third set of alignment marks 14, the fourth set of alignmentmarks 16 and the fifth set of alignment marks 18 of the first mask 10are arranged at top and bottom of the LCD panel area 10-1 oppositely andcorrespondingly. Corresponding to the second mask, the third mask, thefourth mask and the fifth mask, the first mask 10 comprises respectivesets of alignment marks at the top and bottom of the same LCD panel area10-1. Each set of the alignment marks comprises at least two alignmentmarks at the top and bottom. That is as shown in FIG. 5 and FIG. 6, theglass substrate 20 totally comprises three pairs, six alignment marks atthe top and bottom of the same LCD panel area 10-1 but the presentinvention is not limited thereto. Moreover, as shown in FIG. 4 and FIG.6, the opposite distance D₂ between two alignment marks 12 of the secondset oppositely positioned at the top and bottom, the opposite distanceD₃ between two alignment marks 14 of the third set oppositely positionedat the top and bottom, the opposite distance D₄ between two alignmentmarks 16 of the fourth set oppositely positioned at the top and bottomand the opposite distance D₅ between two alignment marks 18 of the fifthset oppositely positioned at the top and bottom are all different onanother, i.e. D₂≠D₃≠D₄≠D₅. As aforementioned, corresponding to the sameLCD panel area 10-1, the second set of alignment marks 22, the third setof alignment marks 24, the fourth set of alignment marks 26 and thefifth set of alignment marks 28 on the glass substrate 20 are arrangedat the top and bottom oppositely and correspondingly. That is,corresponding to the second mask, the third mask, the fourth mask andthe fifth mask, each set of the alignment marks 22, 24, 26, 28 on theglass substrate 20 totally comprises three pairs, six alignment marks atthe top and bottom of each LCD panel area 10-1 for each mask. Meanwhile,the distance D₂ between two alignment marks 22 of the second setoppositely positioned at the top and bottom, the distance D₃ between twoalignment marks 24 of the third set oppositely positioned at the top andbottom, the distance D₄ between two alignment marks 26 of the fourth setoppositely positioned at the top and bottom and the distance D₅ betweentwo alignment marks 28 of the fifth set oppositely positioned at the topand bottom are all different on another, i.e. D₂≠D₃≠D₄≠D₅. As shown inFIG. 7, according to the present invention, the alignment procedurecannot complete if the alignment mark of the wrong mask is being alignedin the alignment system of the lithography system. Therefore, the reworkor even abandonment circumstances of the glass substrate cause ofemploying the alignment mark of the wrong mask can be prevent.Furthermore, the manufacture yield rate of LCD panel can be improved.

Furthermore, the present invention provides another LCD panelphotolithography process, employed in a lithography system formanufacturing a plurality of LCD panel as well to performphotolithography to a glass substrate for manufacturing the plurality ofLCD panels. Please refer to FIG. 4, FIG. 5, FIG. 6 and FIG. 7. Detaildescription of another LCD panel photolithography process according tothe present invention is introduced below:

When the first mask 10 is employed for performing photolithography tothe glass substrate 20 to form a first metal layer, the first mask 10also comprises the set of alignment marks 12 needed for the followingsecond mask, or the two sets of alignment marks 12, 14 needed for thefollowing second mask and following third mask as illustration.Therefore, as the first mask 10 is employed performing photolithographyto the glass substrate 20, the set of alignment marks 22 correspondingto the following second mask, or the two sets of alignment marks 22, 24corresponding to the following second mask and following third mask areformed at the same time. After the following second mask, or thefollowing second mask and following third mask are employed forperforming alignment procedure and photolithography to the glasssubstrate 20 according to the sequence thereof to form patterns, becausethe last mask also comprises the set of alignment marks 14 needed forthe following third mask, or the two sets of alignment marks 16, 18needed for the following fourth mask and following fifth mask asillustration, when the last mask (i.e. the second mask or the thirdmask) is employed for performing photolithography to the glass substrate20, the set of alignment marks 24 corresponding to the following thirdmask, or the two sets of alignment marks 26, 28 corresponding to thefollowing fourth mask and following fifth mask are formed at the sametime. Furthermore, although the set of the alignment marks correspondingto the following one mask, or the two set of the alignment markscorresponding to the following two masks are illustrated asaforementioned, the plurality of sets of alignment marks correspondingto the following three masks, or even following five masks or followingsix masks can be formed at the same time. The number of the alignmentmarks for the following masks is not limited in the present invention.It depends on the preferred plan for the processes of multiple masksaccording to the process demands of the LCD panel. Hereby, the presentinvention can be applied for the LCD panel manufacture processes whichare more complicated and need more masks. The present invention furtherconforms to the rapid development of the LCD panel industry today.

As is understood by a person skilled in the art, the foregoing preferredembodiments of the present invention are illustrative rather thanlimiting of the present invention. It is intended that they covervarious modifications and similar arrangements be included within thespirit and scope of the appended claims, the scope of which should beaccorded the broadest interpretation so as to encompass all suchmodifications and similar structure.

What is claimed is:
 1. A mask, employed in a photolithography process ofa lithography system for manufacturing a plurality of LCD panel, forperforming photolithography to a glass substrate for manufacturing theplurality of LCD panels, characterized in that the mask comprises: aplurality of LCD panel areas, employed for forming patterns on the glasssubstrate; and a plurality of sets of alignment marks, employed forforming a plurality of sets of alignment marks corresponding to theplurality of following masks thereafter, and the plurality of sets ofalignment marks for the plurality of following masks have differentposition coordinates on the mask respectively.
 2. The mask of claim 1,characterized in that at two sides of the same LCD panel area, therespective sets of alignment marks corresponding to the respective maskscomprises at least two alignment marks, and the at least two alignmentmarks of each set of alignment marks have different opposite distances.3. The mask of claim 2, characterized in that at the two sides of thesame LCD panel area, the opposite distances between the at least twoalignment marks are gradually increased or decreased in sequence.
 4. Themask of claim 2, characterized in that at the two sides of the same LCDpanel area, the opposite distances between the at least two alignmentmarks of the each set of alignment marks are gradually increased andthen decreased in sequence.
 5. The mask of claim 1, characterized inthat at the two sides of the same LCD panel area, the plurality of setsof alignment marks have respective x-coordinates and y-coordinatesrelative to an arbitrary side of the same LCD panel area.